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diff --git a/Documentation/i2c/busses/i2c-i801.rst b/Documentation/i2c/busses/i2c-i801.rst new file mode 100644 index 000000000000..2a570c214880 --- /dev/null +++ b/Documentation/i2c/busses/i2c-i801.rst @@ -0,0 +1,182 @@ +====================== +Kernel driver i2c-i801 +====================== + + +Supported adapters: + * Intel 82801AA and 82801AB (ICH and ICH0 - part of the + '810' and '810E' chipsets) + * Intel 82801BA (ICH2 - part of the '815E' chipset) + * Intel 82801CA/CAM (ICH3) + * Intel 82801DB (ICH4) (HW PEC supported) + * Intel 82801EB/ER (ICH5) (HW PEC supported) + * Intel 6300ESB + * Intel 82801FB/FR/FW/FRW (ICH6) + * Intel 82801G (ICH7) + * Intel 631xESB/632xESB (ESB2) + * Intel 82801H (ICH8) + * Intel 82801I (ICH9) + * Intel EP80579 (Tolapai) + * Intel 82801JI (ICH10) + * Intel 5/3400 Series (PCH) + * Intel 6 Series (PCH) + * Intel Patsburg (PCH) + * Intel DH89xxCC (PCH) + * Intel Panther Point (PCH) + * Intel Lynx Point (PCH) + * Intel Avoton (SOC) + * Intel Wellsburg (PCH) + * Intel Coleto Creek (PCH) + * Intel Wildcat Point (PCH) + * Intel BayTrail (SOC) + * Intel Braswell (SOC) + * Intel Sunrise Point (PCH) + * Intel Kaby Lake (PCH) + * Intel DNV (SOC) + * Intel Broxton (SOC) + * Intel Lewisburg (PCH) + * Intel Gemini Lake (SOC) + * Intel Cannon Lake (PCH) + * Intel Cedar Fork (PCH) + * Intel Ice Lake (PCH) + * Intel Comet Lake (PCH) + * Intel Elkhart Lake (PCH) + * Intel Tiger Lake (PCH) + + Datasheets: Publicly available at the Intel website + +On Intel Patsburg and later chipsets, both the normal host SMBus controller +and the additional 'Integrated Device Function' controllers are supported. + +Authors: + - Mark Studebaker <mdsxyz123@yahoo.com> + - Jean Delvare <jdelvare@suse.de> + + +Module Parameters +----------------- + +* disable_features (bit vector) + +Disable selected features normally supported by the device. This makes it +possible to work around possible driver or hardware bugs if the feature in +question doesn't work as intended for whatever reason. Bit values: + + ==== ========================================= + 0x01 disable SMBus PEC + 0x02 disable the block buffer + 0x08 disable the I2C block read functionality + 0x10 don't use interrupts + 0x20 disable SMBus Host Notify + ==== ========================================= + + +Description +----------- + +The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA), +ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of +Intel's '810' chipset for Celeron-based PCs, '810E' chipset for +Pentium-based PCs, '815E' chipset, and others. + +The ICH chips contain at least SEVEN separate PCI functions in TWO logical +PCI devices. An output of lspci will show something similar to the +following:: + + 00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01) + 00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01) + 00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01) + 00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01) + 00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01) + +The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial +Controller. + +The ICH chips are quite similar to Intel's PIIX4 chip, at least in the +SMBus controller. + + +Process Call Support +-------------------- + +Block process call is supported on the 82801EB (ICH5) and later chips. + + +I2C Block Read Support +---------------------- + +I2C block read is supported on the 82801EB (ICH5) and later chips. + + +SMBus 2.0 Support +----------------- + +The 82801DB (ICH4) and later chips support several SMBus 2.0 features. + + +Interrupt Support +----------------- + +PCI interrupt support is supported on the 82801EB (ICH5) and later chips. + + +Hidden ICH SMBus +---------------- + +If your system has an Intel ICH south bridge, but you do NOT see the +SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the +BIOS to enable it, it means it has been hidden by the BIOS code. Asus is +well known for first doing this on their P4B motherboard, and many other +boards after that. Some vendor machines are affected as well. + +The first thing to try is the "i2c-scmi" ACPI driver. It could be that the +SMBus was hidden on purpose because it'll be driven by ACPI. If the +i2c-scmi driver works for you, just forget about the i2c-i801 driver and +don't try to unhide the ICH SMBus. Even if i2c-scmi doesn't work, you +better make sure that the SMBus isn't used by the ACPI code. Try loading +the "fan" and "thermal" drivers, and check in /sys/class/thermal. If you +find a thermal zone with type "acpitz", it's likely that the ACPI is +accessing the SMBus and it's safer not to unhide it. Only once you are +certain that ACPI isn't using the SMBus, you can attempt to unhide it. + +In order to unhide the SMBus, we need to change the value of a PCI +register before the kernel enumerates the PCI devices. This is done in +drivers/pci/quirks.c, where all affected boards must be listed (see +function asus_hides_smbus_hostbridge.) If the SMBus device is missing, +and you think there's something interesting on the SMBus (e.g. a +hardware monitoring chip), you need to add your board to the list. + +The motherboard is identified using the subvendor and subdevice IDs of the +host bridge PCI device. Get yours with ``lspci -n -v -s 00:00.0``:: + + 00:00.0 Class 0600: 8086:2570 (rev 02) + Subsystem: 1043:80f2 + Flags: bus master, fast devsel, latency 0 + Memory at fc000000 (32-bit, prefetchable) [size=32M] + Capabilities: [e4] #09 [2106] + Capabilities: [a0] AGP version 3.0 + +Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043 +(Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic +names for the bridge ID and the subvendor ID in include/linux/pci_ids.h, +and then add a case for your subdevice ID at the right place in +drivers/pci/quirks.c. Then please give it very good testing, to make sure +that the unhidden SMBus doesn't conflict with e.g. ACPI. + +If it works, proves useful (i.e. there are usable chips on the SMBus) +and seems safe, please submit a patch for inclusion into the kernel. + +Note: There's a useful script in lm_sensors 2.10.2 and later, named +unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to +temporarily unhide the SMBus without having to patch and recompile your +kernel. It's very convenient if you just want to check if there's +anything interesting on your hidden ICH SMBus. + + +---------------------------------------------------------------------------- + +The lm_sensors project gratefully acknowledges the support of Texas +Instruments in the initial development of this driver. + +The lm_sensors project gratefully acknowledges the support of Intel in the +development of SMBus 2.0 / ICH4 features of this driver. |